The present invention relates to a method for controlling waterborne disease organisms, parasites and other infectious agents that afflict man, plants and animals, both domestic and wild. These infectious agents are a serious concern throughout the world. The disciplines of parasitology, epidemiology, epizootiology, and plant pathology have created nomenclature which is over-specific for the purpose of this invention. Various terms such as xe2x80x9cinfectious agentxe2x80x9d or xe2x80x9cpathogenxe2x80x9d are used interchangeably in this application to include parasites, bacteria, protozoans, fungus, etc. and their infectious stages such as spores, oocysts, etc. that are injurious to man, plants and animals and are of a size which can be removed from the water by the filtration of bivalve mollusks.
The present invention combines knowledge from disparate disciplines within modern society, specifically, the bivalve mollusk growing industry and the public health sector covering an array of specialties, including but not exclusive to veterinary medicine, plant pathology and human health. Normally, these sectors are mutually exclusive for reasons explained in greater detail below. Applicant has found that the marriage of these disparate disciplines may provide results advantageous to them.
Numerous laws and powerful public opinion separate bivalve mollusk producers from those working to prevent the spread of communicable diseases. The present invention will require close cooperation between the disciplines to create any significant benefit.
Some of the biological processes in the present invention, which are described below, were just recently discovered by scientists in the human public health sector looking for ways to identify disease sources and monitor waterborne pathogens. The results of these studies have been viewed by some health and environmental officials as a reason to further restrict bivalve mollusk production. Pathogen/parasite contaminated waters and bivalve mollusk growing areas have historically been strictly separated in order to protect the public from waterborne disease organisms. However, these recent discoveries show that various bivalve mollusks are capable of destroying a variety of waterborne pathogens and parasites known to be very harmful to humans, animals and even plants to the point of injury or lethality (see FIGS. 1 and 2). FIG. 2 shows fluorescent In Situ Hybridization (FISH) and immunofluorescent antibody (IFA) images of Giardia lamblia cysts (panels A, B and C) and Cryptosporidium parvum oocysts (panel D). Viable G. lamblia cyst (panel A), nonviable G. lamblia cyst (panel B), and cyst shell (=nonviable cysts) with structural wall damage (arrow) (panel C) Viable C. parvum oocyst (arrow) and oocyst shells (nonviable oocysts) (arrow heads) (panel D). Note structural damage of the oocyst wall and a small gap between the oocyst wall and the internal structures of viable oocyst. Scale bar 20 micrometers in panels A, B and C; and 10 micrometers in panel D. See Graczyk, Thaddeus K., D. Bruce Conn, Ronald Fayer, David J. Marcogliese, Yves de Lafontaine, Alexandre J. Da Silva, Norman J. Pieniazek, Asian Freshwater Clams (Corbicula fluminea) and Zebra Mussels (Dreissena polymorpha) as Biological Indicators of Contamination With Human Waterborne Parasites, Aquatic Invaders, Volume 13, Number 4, Winter 2002. The present invention would in fact reverse the practice of complete separation in order to more fully protect the public, man""s food supply and our living resources. The current practice of separation produces safer seafood in decreasing amounts. The present invention would greatly enhance public safety over the current practice by providing safer swimming areas, potable drinking water, safer irrigation water, and in fact, could even be used to produce safer seafood by decreasing the number of pathogens in bivalve mollusk growing areas. Historically, when disease outbreaks have occurred, there were legal battles and bad press for both sides. The divide between the two groups was further widened by longstanding laws strongly enforced by health and environmental officials.
Because of this, bivalve mollusks are normally produced in waters where pathogen levels are not a problem. Existing Domestic and Foreign Laws require that bivalve mollusks produced for human consumption come from uncompromised, unpolluted water. The National Shellfish Sanitation Protocol (NSSP) was developed by the Interstate Shellfish Sanitation Commission and is administered by the United States Food and Drug Administration. As new techniques come on line to identify these pathogens, bivalve mollusk production areas are shrinking. For example, closure of parts of Cuckold Creek, St. Inigoes Creek and Carthagena Creek by the Maryland Department of the Environment in October, 2002, illustrate this point. See FIGS. 3 and 4. New entrants into this field need to attempt to avoid pathogen polluted waters because they will not be allowed to sell their product. Established growers of bivalve mollusks avoid any mention of any waterborne disease in conjunction with their product. Bivalve mollusk producers"" reputations are built by selling a safe and healthful food product to the public. To remain in business, they need to avoid waters polluted with disease organisms and, beyond that, even the mention of it.
Public health providers are members of a much larger group than bivalve mollusk producers. Because most disease monitoring prevention and control is done by them for the general public they see their task as providing a barrier between the public and diseases. To accomplish this, they prevent the harvest of contaminated bivalve mollusks or even bivalve mollusks that may have the possibility of contamination.
The most obvious source of waterborne pathogens from domestic sources is the point source which typically comes out the end of a pipe. The pathogens thus discharged usually come from poorly treated or untreated human sewage and wastewater. The owners of facilities with discharge pipes are required by law to clean up the water prior to its release. However, accidents can happen, including acts of nature, which produce spills containing infectious organisms. Older, overworked systems have plumbing failures and sometimes overflow when storm water mixes with wastewater. One prime example of an older overworked system can be found in Washington, D.C. There, storm water run-off and sewage are combined in the same pipes. Numerous other smaller municipalities from the same era followed the same engineering model. After major storm events the excess water causes many of them to have serious overflow problems. Applicant has been unable to find a single instance where success was achieved in cleaning up the body of water into which these systems overflowed. Instead, fines and penalties were imposed to discourage polluters from doing it again. The thrust of existing regulation and legislation is to punish all polluters in an effort to force intentional polluters to clean up the water. It is hard to envision, due to modern education and the severity of the penalties, that there are many intentional polluters left. If they accept punishment, they admit guilt and have less money to do what they are being asked to do. Admission of guilt is not a solution to the problem, and, as such, many releases just go unreported.
Because bivalve mollusk producers historically have been required to use clean water to grow their crop, they have not looked into intentionally growing bivalve mollusks in polluted waters using their xe2x80x9cproductxe2x80x9d to reduce or remove the very pathogens that contaminate it. Until very recently no one knew how these pathogens were processed by the bivalve mollusks. Most of the literature dealing with this incorrectly assumed that the bivalve mollusks concentrate the pathogens making them more dangerous, or merely passed the infectious material on through, purging it from their bodies in a still viable form capable of contaminating other bivalve mollusks. Certainly no-one seemed to be considering these infectious agents as prey species dined on by bivalve mollusks. This was because the technology that allows the very identification of many of these smaller microbial problems has just come on line. One example is the MERIFLOUR test by Meridian Diagnostic Inc. See Thaddeus K. Graczyk, Ronald Fayer, Michael R. Cranfield, and David Bruce Conn, In vitro Interactions of Asian Freshwater Clam (Corbicula fluminea) Hemocytes and Cryptosporidium parvum Oocysts, Applied and Environmental Microbiology, July, 1997, p. 2910-2912. Bivalve mollusk growers are pressured by public health scares concerning food born illness caused by eating raw or partially cooked bivalve mollusks. Recently Ralph Nader promoted the idea that the sale of raw bivalve mollusks for human consumption should be banned entirely under federal law. The historical method, currently in use, for determining if bivalve mollusks are safe for human consumption is to look for more easily identified indicator bacteria in the water. The presence of these indicator organisms was believed to be a warning of the presence of fecal contamination by which enteric pathogens are transmitted. This method was determined to be flawed in 1986 in a study published by the United States Environmental Protection Agency (EPA) which showed a negative correlation between gastrointestinal illness of swimmers and the occurrence of the indicator bacteria Escherichia coli. This same EPA study called for an additional study to deal with the use of this same indicator organism in determining the extent of bivalve mollusk harvesting waters. Unfortunately, this call was ignored and the study was never done. The continued misidentification of clean water has further alienated the two disciplines. See Ambient Water Quality Criteria for Bacteriaxe2x80x941986, USEPA, Office of Water, Criteria and Standards Division, Washington, D.C. 20460, EPA440/5-84-002 (January, 1986, at p. 11, paragraph 2).
Because of the devastating economic impact on sales that immediately follows any reported outbreak of illness, or even the hint of a connection to this kind of event, new discharge points are strongly opposed by bivalve mollusk growers and harvesters alike. The recent deaths of 13 people in Cleveland, Ohio further illustrates this point. Cryptosporidium parvum which got through the city""s drinking water treatment facility was determined to be the causative agent in these deaths. Press reports of this event included the fact that, several years before, this same organism had been found in Maryland oysters. The stories recalled other problems reaching back years. This information was released by the news media at the beginning of Maryland""s oyster season in the fall of 2002, in the Washington D.C. area. The stories preceded an immediate drop in industry sales. No deaths or other health problems caused by C. parvum had actually been attributed to eating Maryland oysters.
Environmental groups have recently targeted the non-point source polluter, following events such as the recent Pfeisteria outbreak in Maryland waters of the Chesapeake Bay. Regulations were quickly written to control this newly recognized threat to public health. To the general public, a non-point source polluter usually means the xe2x80x9cfarmerxe2x80x9d. It also includes the run-off from forest land, urban streets and developed land. The farmer and other new targets of regulation are being told not to let any pollutants get into the water. This group is still putting together methods to comply with the new rules. The political division between non-point source polluters and bivalve mollusk producers is also growing stronger due to the way the Maryland""s Pfeisteria outbreak was handled by politicians and the press.
Phosphorus fertilizer from chicken production farms was blamed for the outbreak. Reducing or stopping the release of phosphorus was seen as the solution to this problem. Using bivalve mollusks to reduce or control the numbers of this dinoflagellate were never discussed or considered as an alternative option. See Blue Ribbon Citizens Pfiesteria Action Commission, Final Report, November, 1997, printed by the Maryland Department of General Services; Graphics and Reproduction Services Department available online at http://www.dnr.state.md.us/bay/cblife/algae/dino/pfiesteria/hughes_commission_report.pdf.
Infectious agents are carried by water throughout the hydrological cycle. Man""s activities as well as natural processes contaminate this water with pathogens every step along the way. Birds flying over swimming in, or perching over open water defecate, releasing the infectious stage of parasites and pathogens into open water. Beavers, muskrats and other mammals live in the water and are another source of infectious agents such as Cryptosporidium parvum. All forms of avian and mammalian life both wild and domestic require water and come to it to drink. This, combined with the normal bodily functions of these animals and direct contact with the water, release these infectious agents into the water. Run-off from land carries with it these same organisms and others from plants, various forms of wildlife, domestic animals and man. This is the natural dispersal method for these infectious agents in their search for a new host to parasitize so that they can multiply and carry on their species. These organisms are so small they can even hitch-hike on dry materials that have been lifted into the air, picked up by the water droplets in clouds to fall with the precipitation.
Precipitation, usually in the form of rain, can fall directly on open water or on land. Rain and melting snow pick up microbes from the land and carry them to open water. This pathogen/parasite loaded water can get to open water rapidly in the form of run-off. Water from failed septic systems can seep through highly permeable soil into open water laden with bacteria, parasites and pathogens. This is even more pronounced in areas underlain by limestone deposits where water flows through cracks in the rock feeding underground streams and rivers. Water bearing these biological hazards eventually makes its way to open water such as ponds, streams, and lakes and then on to the ocean by way of our estuaries.
Man pumps water out of the ground and then returns it to the ground, in many cases contaminated with infective agents. Although most direct discharges of raw sewage into open water have been or are being dealt with, failed systems can release these microbes into open water.
Until recently, many boats had toilets with direct overboard discharge. The numbers of these are dropping but they still remain a problem in many areas and create a potential biological hazard.
Many forms of infectious agents have adapted to surviving long periods without a host in the environment. Adaptations such as small size, protective coatings and reduced metabolism allow them to withstand severe environmental factors such as drying, freezing and extreme heat. One example is Cryptosporidium parvum which is known to live and remain capable of infecting a host after 3 months in artificial seawater at 20xc2x0 C. See Graczyk, Thaddeus K., C. A. Farley, R. Fayer, E. J. Lewis, and J. M. Trout, Detection of Cryptosporidium Oocysts and Giardia cysts in the Tissues of Eastern Oysters (Crassostrea virginica) Carrying Principal Oyster Infectious Diseases, Journal of Parasitology, 84(5), 1998, p. 1039. Because of this, infectious agents and parasites can travel long distances borne on water currents. Wherever and whenever the water flows with sufficient speed to keep them suspended, they will be carried along. Due to the slow sinking rate of some of the smaller of these organisms, they can be carried along in very slow moving water.
The present invention is intended to teach how the process of transmittal can be broken or reduced with the use of bivalve mollusks, by cutting the transference of infectious and parasitic agents from one host to the next. Many parasites and infectious agents have waterborne phases within their life cycle which can be interrupted by the present invention.
Water contaminated with infectious agents presents a number of problems for mankind. The motile flagellated asexual spores of Phytophthora are saprobes and parasites. The name of this group means xe2x80x9cplant destroyerxe2x80x9d and its members damage or destroy many kinds of agriculturally important plants. Others can be toxic as in the case of Pfeisteria, a fish parasite that produces chemicals toxic to man, or dangerous to human or animal health in other ways. These organisms are diverse and cover a wide range which includes micro fauna, flora, protista, chromyxa, bacteria, and fungi. They can be either infectious or parasitic in nature. Such microorganisms as Giardia, Cyclospora and Cryptosporidium can be debilitating or lethal to man. Water carrying these or other infective agents is of little use for drinking or irrigation without costly filtration processes such as reverse osmosis or nanofiltration. Even its recreational value is greatly reduced. This cost of course must be passed on to the consumer. Two-thirds of the households in Maryland depend on surface water sources for their drinking water. See Klein, Richard D., Opportunities to Enhance Breton Bay, published by the Potomac River Association, Jul. 11, 2001. These waterborne diseases also put at risk agricultural operations such as livestock production and restrict the use of this water for irrigation of crops. Irrigation water holding human infectious organisms is useless for vegetable and fruit crops, especially those destined to be eaten raw. Because of this, scientists have come up with numerous ways to correct the problem. Most of them deal with toxic chemicals or sterilization techniques to prevent these agents from entering the water or food supply. Our water systems are threatened by agents which are increasingly resistant to sterilization technology such as the life threatening parasite Cryptosporidium parvum. The cost of making the water safe rises dramatically and the risk can increase to the point that entire bodies of water can no longer be used or even considered for utilization. This places higher and higher demands on other sources such as aquifers which if overtaxed will collapse and be destroyed. With a growing population, this problem is not likely to go away in the near future and practical, efficient, and less expensive methods are needed to make open surface waters safe for use by mankind.
On riverine systems, one town""s intake for potable water is downstream from another""s wastewater treatment plant outfall. On long rivers like the Mississippi, the number of times water is reused from the head waters to it""s final destination in the gulf of Mexico allows many chances for accidental introduction of infectious and parasitic agents harmful to man his living assets and society in general.
The present invention is a non-toxic, environmentally positive solution to the problem and does not produce a waste product, that must be disposed of. The present invention could be useful in re-opening areas for human uses that are currently closed to those uses.
Bivalve mollusks are highly efficient in capturing food by filtering small particulate matter from the water. As we now know, these infectious agents are bivalve mollusk food. The current invention takes advantage of this fact. One of three fates usually awaits these infectious agents once they have been filtered from the water: 1)Extracellular digestion destroys many of them within the gastrointestinal tract of the bivalve mollusk; 2)Intracellular digestion also takes place when these agents are phagocytized by the free ranging blood cells (amebocytes) (Barnes, p. 321) which directly bathe the tissues of bivalve mollusks. See FIG. 1; Photomicrograph showing migrating hemocyte of the Asian freshwater clam (C. Fluminea) with a phagocytosed C. parvum (strain AUCP-1) cocyst (arrow) and free, non-phagocytosed oocysts (arrowheads) Bar=10 xcexcm. See Graczyk, Thaddeus K., Ronald Fayer, Michael R. Cranfield, and David Bruce Conn, In Vitro Interaction of Asian Freshwater Clam (Corbicula fluminea) Hemocytes and Cryptosporidium parvum Oocysts Applied and Environmental Microbiology, July 1997, p. 2911. 3)Those that escape the digestive processes are encapsulated in feces or pseudofeces and expelled by the bivalve mollusk in a form that rapidly sediments out due to large particle size and specific gravity. Once on the bottom, they may be further processed and digested by benthic deposit feeders planted or encouraged to colonize in the plume area (area of deposition described later in the inventive process). Those that are not destroyed by the above methods become candidates for burial through bioturbation or direct burial in the sediments by the additional material piled on top of them. They become entombed and can no longer cause harm. Over time these buried organisms will eventually senesce and die or be consumed by burrowing biota.
The method for controlling waterborne diseases and parasites of the present invention acts to remove these microbes from the water-column and destroy them or entomb them in the bottom; in either scenario they are eventually turned into harmless organic material. The present invention acts to interrupt the pathogen/parasite life cycle between hosts and therefore will have a positive effect on epidemiology, plant pathology and epizootiology.
As more material is deposited onto the bottom, these parasites and pathogens are buried and can remain there indefinitely unless disturbed. However, the life-span of these microbes is not indefinite and they eventually succumb. In this way, those parasites and pathogens that are not digested by the bivalve mollusk are removed from the water column through sedimentation. Encapsulation of parasites and pathogens in the sticky feces and pseudofeces produced by the bivalve mollusk virtually precludes their resuspension. So, they remain on the bottom and are buried as more and more particulate matter is added on top of them. This burial processes is further accelerated by a process known as bioturbation as active benthic organisms turn over the sediment.
The present invention teaches how bivalve mollusks can be used to remove infectious agents from open waters. A bivalve mollusk farm is known as a water purifying means. An example of such a farm is described in Sea Frontiers 1973. See Sea Frontiers, Volume 19, No. 6, November-December, 1973, p. 368-373. This article fails to teach the use of oysters in a natural body of water. Although the article teaches the use of oysters as a water purifying means, it fails to deal with the direct use of the bivalve mollusks as a method of controlling parasites and pathogens in a natural body of water.
The present invention significantly differs from Applicant""s prior patent, U.S. Pat. No. 6,391,201 (the ""201 patent).
Site selection for applicant""s patented system requires a carbon source for the anaerobic bacteria needed in de-nitrification when reducing nutrient levels. Even more significantly, areas known or suspected of having disease organisms, parasites and other infectious agents that afflict man were a concern when choosing edible bivalves for post harvest value.
System deployment varies significantly between the present and prior invention in that the prior invention is defined as completely off bottom and set at specified distances from the surface. This was done to facilitate filtration by the bivalves of specific strata within the water column. The present invention is designed to filter the entire volume of water to maximize the removal of the target organisms.
Use of the respective systems differs significantly as well. The goal of the prior invention is to change the chemical composition of areas of open water in order to control environmental fertility levels. To do this, in part, the prior invention controls population levels of organisms capable of photosynthesis. The present invention, on the other hand, is used to lower levels of an entirely different group of target organisms, specifically ones capable of causing disease, parasitizing hosts or producing infections. The present invention is deployed to remove these organisms from areas of open water making that water safe for a variety of uses. Photo-synthetic capability of these organisms is not a criteria for targeting them.
The present invention relates to a method for controlling waterborne infectious agents. The present invention is designed to return polluted waters to conditions that can again facilitate production of food, be used for recreation, and be healthy areas for water dependent human activities.
The present invention can also be used to reduce the number of infectious agents for potable water supplies, agriculture and other uses. Examples of agricultural uses would be to treat water in ponds used for irrigation of vegetables, fruit, livestock forage or other crops or for watering livestock. The present invention provides a method of biological control for the reduction and destruction of these infectious agents. It provides a means to remove these organisms from the water column in open waters. The goal of these removal efforts is to either reach levels that are non-infectious or to lower levels to a point where they can be more easily and less expensively treated for use of the water. In this regard, it is known that there is an exposure level threshold below which certain infectious agents are not capable of causing disease. Once in place, the present invention can be employed to maintain the desired reduced levels.
The present invention can be used in eutrophic, mesotrophic, and oligotrophic conditions; in fresh, estuarine and salt water, and from the tropics to the sub arctic. The present invention can be practiced anywhere that large numbers of filter feeding bivalve mollusks, which produce pseudofeces, can be retained and where phytoplankton production can be counted on to support them. If these first two criteria are met, the third component, removal of infectious agents, is certain. In certain instances, greater success can be achieved when the present invention is coupled with a Biological Nutrient Control System (BNC(trademark)) as disclosed in Applicant""s prior U.S. Pat. No. 6,391,201, and be located in slow to intermediate water flow. However, this flow can be provided by mechanical means whenever necessary, such as pumps, blowers, paddle wheels, etc., and fast currents can be slowed with weirs, dams or other means.
The present invention consists of a process starting with waterborne infectious agents entering a water body from a variety of sources. Such sources include point sources and non-point sources which include but are not limited to land runoff, ground water, precipitation, release from disturbed bottom sediments, directly introduced by animals, and deposition of materials by wind.
Within the water body, the invention is effective on those waterborne microscopic infectious agents known to be of a particle size normally filtered from the water by bivalve mollusks when actively feeding, with one caveat. The invention is not designed to be effective against infectious agents that adversely effect the health of the mollusks in the arrays.
By preference, bivalve mollusks that produce pseudofeces are held in aquaculture production and used to filter waterborne microscopic disease organisms and parasites from the water. Non-pseudofeces producing bivalves are less effective (see 1 below) In the course of feeding on an assortment of particulate and colloidal materials found in the water, the bivalve mollusks process this material in two (2) ways:
1) Particles that are too large or too heavy for the bivalve mollusks to consume are sorted, and then incorporated into sticky pseudofeces that are then ejected back into the water. The pseudofeces then falls to the bottom. This sorting process does not break down these particles and the particles may have attached to them or embedded in them live infective agents which are incorporated into the pseudofeces.
2) Particles suitable for food are ingested followed by digestion either extracelluarly or intracellularly (wherein the particles are phagocytized by hemocytes). Extracted nutrients are incorporated into the bivalve mollusks, inactivated particles are incorporated into solid waste and any live infectious agents that survive the digestive process are encapsulated in the feces. See Craczyk, Thaddeus K., D. Bruce Conn, Ronald Fayer, David J. Marcogliese, Yves de Lafontaine, Alexandre J. Da Silva, Norman J. Pieniazek, Asian Freshwater Clams (Corbicula fluminea) and Zebra Mussels (Dreissena polymorpha) as Biological Indicators of Contamination With Human Waterborne Parasites, Aquatic Invaders, Volume 13, Number 4, Winter, 2002.
Sticky mucous binds both the feces and pseudofeces containing live infectious agents when it is ejected by the bivalve mollusks. This effectively prevents resuspension of waste products. This is useful to the bivalve mollusks in that it prevents re-ingestion by the same or other filter-feeding bivalve mollusks. As more material is ejected and settles to the bottom and is deposited, the organisms contained in the bivalve mollusks"" feces and pseudofeces are sequestered in the sediments and removed from the water by direct burial in the sea bed. Benthic deposit feeders such as worms and certain clams may then consume this material a second time destroying more of the organisms.
This sequence of events changes these infectious agents into harmless material.
The processes of sequestration, and burial described above have been documented in fresh, estuarine, and salt water. See Wetzel, Robert G. Limnology, CBS College Publishing, Saunders College Publishing, ISBN 0-030057913-9 767PP.
The system used to conduct the process described above will be described in greater detail below.
Accordingly, it is a first object of the present invention to provide a method for biological control of waterborne infectious agents.
It is a further object of the present invention to provide such an invention wherein bivalve mollusks are employed to disinfect a body of water.
It is a still further object of the present invention to provide a process practiced in moderate to slow moving water.
It is a still further object of the present invention to provide such a process in which waterborne diseases and parasites are transferred to the bottom sediment as a method of control as the process is practiced.
It is a yet a further object of the present invention to provide such an invention in which means are provided to contain bivalve mollusks within a prescribed area, with bivalve mollusks suspended above the bottom.
It is a yet further object of the present invention that it may be practiced in conjunction with bivalve mollusks or other benthic biota planted on or in the bottom to further increase the efficiency of the invention.